CAJ | 학술논문

为探索木塑复合材料的老化规律，改善木塑产品的老化性能，该文以化学发泡法制备的竹粉/聚丙烯（polypropylene，PP）发泡复合材料为研究对象，采用户外自然老化方式，研究自然老化对发泡复合材料材色、弯曲蠕变性能、流变性能的影响；同时为改善发泡复合材料的老化性能，研究了抗老化剂对发泡复合材料自然老化性能的影响。结果表明：抗氧化剂B225和抗紫外线剂UV770均可改善复合材料的自然老化变色，减缓复合材料的老化褪色，提高复合材料老化后的弯曲蠕变性能和流变性能。在提高复合材料材色稳定性和初始刚性方面，添加质量分数为0.6% B225的效果较优，其次是添加0.3%B225+0.3%UV770、最后是添加0.6% UV770；而添加0.3% B225+0.3% UV770的复合材料，其流变性能稳定性较佳。自然老化12个月后，未添加抗老化剂的复合材料产生的色差?E*为22.8，而添加0.6% B225、0.6% UV770、0.3% B225+0.3% UV770的复合材料，其?E*分别为14.2、17.6和16.8。自然老化12个月后，添加抗老化剂的复合材料，其产生的蠕变应变减小且弯曲性能保留率增大。动态频率扫描结果显示，自然老化会降低复合材料的储能模量、损耗模量、复数黏度和平均分子量，缩短松弛时间；添加抗老化剂不仅可提高复合材料的初始流变性能，而且可改善复合材料的流变性能稳定性。研究结果为进一步探索木（竹）塑发泡复合材料的老化规律及木塑生产实践提供数据和理论参考。
위탐색목소복합재료적노화규률，개선목소산품적노화성능，해문이화학발포법제비적죽분/취병희（polypropylene，PP）발포복합재료위연구대상，채용호외자연노화방식，연구자연노화대발포복합재료재색、만곡연변성능、류변성능적영향；동시위개선발포복합재료적노화성능，연구료항노화제대발포복합재료자연노화성능적영향。결과표명：항양화제B225화항자외선제UV770균가개선복합재료적자연노화변색，감완복합재료적노화퇴색，제고복합재료노화후적만곡연변성능화류변성능。재제고복합재료재색은정성화초시강성방면，첨가질량분수위0.6% B225적효과교우，기차시첨가0.3%B225+0.3%UV770、최후시첨가0.6% UV770；이첨가0.3% B225+0.3% UV770적복합재료，기류변성능은정성교가。자연노화12개월후，미첨가항노화제적복합재료산생적색차?E*위22.8，이첨가0.6% B225、0.6% UV770、0.3% B225+0.3% UV770적복합재료，기?E*분별위14.2、17.6화16.8。자연노화12개월후，첨가항노화제적복합재료，기산생적연변응변감소차만곡성능보류솔증대。동태빈솔소묘결과현시，자연노화회강저복합재료적저능모량、손모모량、복수점도화평균분자량，축단송이시간；첨가항노화제불부가제고복합재료적초시류변성능，이차가개선복합재료적류변성능은정성。연구결과위진일보탐색목（죽）소발포복합재료적노화규률급목소생산실천제공수거화이론삼고。
Wood-plastic composite (WPC) has environmental and economical advantages and has been extensively applied and studied. Weathering causes negative changes in the surface appearance, mechanical properties and surface chemical properties of the WPC products. Thus, to explore the weathering mechanism of WPC, improve its durability and provide some data and guide for WPC production, the natural weathering performance of bamboo powder/polypropylene (PP) foamed composites was researched. The composites containing 33% bamboo flour, 1% modified AC (azodicarbonamide) foaming agent and different anti-aging agents were prepared by the injection molding. The composites were exposed to outdoor natural weathering from October 2012 to October 2013 in Fuzhou (26°08′N, 119°18′E), the southeast of China. The effects of natural weathering on the composites’ color, flexural creep behavior and rheological behavior were investigated. Meanwhile, the effects of the antioxidant B225 and anti-ultraviolet agent UV770 on the composites’ weathering performance were also studied. The B225 is a complex antioxidant agent using Tetra-[methylene-β-(3, 5-di-tert-butyl-4-hydroxyphenyl)-propionate] methan and Tns-(2, 4-di-tert-butyl)-phosphite, with a ratio of 1:1. The UV770 is bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate. The results showed that both the B225 and the UV770 could slow down the color fading and improve the color stability during weathering. After weathering for 12 months, the color change reduced from22.8 for the composites without adding antioxidant to 14.2, 17.6 and 16.8 for the composites contained with 0.6% B225, 0.6% UV770, 0.3% B225 and 0.3% UV770, respectively. The B225 has more positive effect on color stability of the composites than UV770. According to authors’ prior research, the influence of natural weathering on the composites’ color was similar with the artificial accelerated weathering. The color change caused by the natural weathering for 12 months was equal to that by accelerated weathering of xenon-arc radiation with water spray for 0.4 months, and also was similar to that by the accelerated cycling of water immersion followed by freeze-thaw cycle at the temperature of -40-60℃for 22 times. Due to the combined effect of the creep and long-term weathering, particularly at 75% stress level, the creep strain increased, and the flexural modulus and flexural strength declined. The composites containing the anti-aging agents also had higher creep resistance for their decreased creep strain and enhanced residual flexural properties. After creep test for 5400 s at 75% stress level, the control sample weathered for 12 months fractured but the retention rates of flexural modulus and flexural strength of composites with anti-aging agents were 92.2%-96.1%. The rheological results of composites with respect to frequency sweep ranging from 0.01 to 100 Hz at 190℃ indicated that the natural weathering decreased the storage modulus, loss modulus, complex viscosity and relaxation time of composites. The decreased crossover modulus, relaxation time and average molecular weight confirmed the photodegradation of composites caused by natural weathering. Adding anti-aging agents improved both the rheological properties of the unweathered composites and the rheological stability of the weathered ones. The B225 and UV770 had synergistic effect in terms of rheological behavior. The weathered composites contained with 0.3% B225 and 0.3% UV770 showed the highest rheological stability for its higher residual moduli and relaxation time. It is recommended that using these 2 types of anti-aging agents to prepare the WPC.